Merge pull request #4198 from alexlarsson/fix-setuid

archive: Fix the storing of setuid bits, etc

archive/archive.go

@@ -187,19 +187,24 @@ func addTarFile(path, name string, tw *tar.Writer) error {
 }
 
 func createTarFile(path, extractDir string, hdr *tar.Header, reader io.Reader) error {
+	// hdr.Mode is in linux format, which we can use for sycalls,
+	// but for os.Foo() calls we need the mode converted to os.FileMode,
+	// so use hdrInfo.Mode() (they differ for e.g. setuid bits)
+	hdrInfo := hdr.FileInfo()
+
 	switch hdr.Typeflag {
 	case tar.TypeDir:
 		// Create directory unless it exists as a directory already.
 		// In that case we just want to merge the two
 		if fi, err := os.Lstat(path); !(err == nil && fi.IsDir()) {
-			if err := os.Mkdir(path, os.FileMode(hdr.Mode)); err != nil {
+			if err := os.Mkdir(path, hdrInfo.Mode()); err != nil {
 				return err
 			}
 		}
 
 	case tar.TypeReg, tar.TypeRegA:
 		// Source is regular file
-		file, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, os.FileMode(hdr.Mode))
+		file, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, hdrInfo.Mode())
 		if err != nil {
 			return err
 		}
@@ -249,7 +254,7 @@ func createTarFile(path, extractDir string, hdr *tar.Header, reader io.Reader) e
 	// There is no LChmod, so ignore mode for symlink. Also, this
 	// must happen after chown, as that can modify the file mode
 	if hdr.Typeflag != tar.TypeSymlink {
-		if err := os.Chmod(path, os.FileMode(hdr.Mode&07777)); err != nil {
+		if err := os.Chmod(path, hdrInfo.Mode()); err != nil {
 			return err
 		}
 	}